Comparison of eotaxin‐3 biomarker in patients with eosinophilic oesophagitis, proton pump inhibitor‐responsive oesophageal eosinophilia and gastro‐oesophageal reflux disease

BackgroundProton pump inhibitor-responsive oesophageal eosinophilia (PPI-REE) is a recently described entity which resembles oeosinophilic oesophagitis (EoE), yet responds to acid suppressive treatment. AimTo determine whether EoE shares similar staining features with PPI-REE or with gastro-oesophageal reflux disease (GERD). MethodsThis retrospective study consisted of patients with an established diagnosis of EoE, PPI-REE, or GERD identified from a database during a 1-year period. Immunohistochemistry (IHC) analysis was performed specifically targeting eotaxin-3 antibodies. All sections were qualitatively (intensity) and quantitatively (percentage of cells stained) assessed independently by two blinded pathologists. ResultsThe cohort consisted of three groups of patients: EoE (n=22), PPI-REE (n=23) and GERD (n=23) for a total of 68 patients. Study demographics included mean age 39 (14) years, 75% male and 77% Caucasian. There was a significant difference in the eotaxin-3 staining among EoE, PPI-REE and GERD groups [mean score (s.d.): 1.2 (1.2), 0.8 (1.0), 0.3 (0.7), P=0.006]. Staining scores of EoE patients were significantly higher compared with GERD (P=0.002) and a trend towards significance was seen between EoE and PPI-REE (P=0.054). There was also a significant difference in EoE staining intensity score among the three groups (P=0.006). Intensity scores of EoE were significantly higher compared with GERD [1.0 (0.9) vs. 0.22 (0.52), P<0.001]. There was no significant difference between EoE and PPI-REE groups [1.0 (0.0) vs. 0.52 (0.75) P=0.094]. ConclusionsA difference in eotaxin-3 staining was seen in the three groups of patients with oesophageal eosinophilia. Eotaxin-3 can distinguish EoE from GERD, but not from proton pump inhibitor responsive-oesophageal eosinophilia.